Contention Ratio Explained: Why Shared Internet Isn't Always What You Paid For
You sign up for a 100 Mbps business internet plan. The sales page promises fast, reliable connectivity. The plan costs more than the residential equivalent, and you feel reasonably confident you're getting something decent.
Then 9:30 AM arrives. Your video call stutters. File uploads crawl. Staff start complaining. You run a speed test and see 18 Mbps where you expected 100.
By 7 PM, when the office is empty, everything is blazing fast again.
This pattern — fast in the early morning or evening, slow during business hours — is one of the most common complaints Australian businesses have about their internet. And in most cases, the culprit is not a fault, not a misconfiguration, and not something your IT person can fix. It is the result of contention.
Understanding contention is one of the most practically useful things a business owner can do when evaluating internet plans. It explains the gap between what is advertised and what is delivered, and it points directly to what to look for when choosing an RSP (retail service provider).
Why Your 100 Mbps Plan Doesn't Always Deliver 100 Mbps
Broadband plans are sold using "up to" speed figures. That qualifier is doing a lot of work.
When a provider sells you a 100 Mbps plan, they are typically not reserving 100 Mbps of capacity exclusively for your connection. Instead, they are provisioning a shared pool of bandwidth and assigning access to that pool across many customers. The assumption — and it is an engineering assumption built into every mass-market broadband product — is that not all customers will be using their full allocated speed simultaneously.
Most of the time, that assumption holds. At midnight, residential customers are mostly asleep. Traffic across the network is low, and any individual user can pull speeds close to their plan limit because the pool is largely unused.
But during business hours, that assumption breaks down for business customers. Your staff, your customers' staff, and thousands of other businesses on the same network infrastructure are all trying to do the same things at the same time: join video calls, access cloud software, upload documents, download files. Demand spikes precisely at the hours when your business needs the connection most.
The technical mechanism behind this gap between plan speed and real-world speed is contention ratio.
What Is Contention Ratio?
Contention ratio is the number of users sharing a given amount of bandwidth at the network level.
A contention ratio of 50:1 means that, in the worst case, 50 customers are sharing the capacity provisioned for a single customer. If that provisioned capacity is 100 Mbps and all 50 customers demand full speed simultaneously, each gets 2 Mbps — a fraction of what they paid for.
In practice, a 50:1 ratio does not always result in a 50-way split of capacity. Not all customers are active at the same moment. A residential customer might be streaming video at low bitrate while their household is asleep, another might be idle, another uploading a single file. The statistical distribution of usage tends to smooth out the worst-case scenario under normal conditions.
The problem arises when the customer profile is homogenous. A business precinct — a CBD office building, a business park, a commercial strip — is filled with customers who all operate on the same schedule. From 8:30 AM to 5:30 PM, demand is concentrated. Everyone on that shared infrastructure is active at the same time. The statistical smoothing that makes high contention ratios workable in residential contexts largely disappears.
This is why contention is a more acute problem for businesses than for residential users, and why the time of day matters so much. The network can physically carry the traffic — it is just trying to carry too much of it at once across infrastructure that was not provisioned to handle the concurrent load.
For context, consumer-grade NBN plans from large RSPs have historically operated at contention ratios ranging from 20:1 to well over 100:1 depending on the RSP, the time period, and the specific network node. Business-grade services aim for tighter ratios — commonly cited targets in the industry are around 10:1 to 20:1 for business NBN, and 1:1 (no contention) for dedicated enterprise circuits.
How Contention Works in the NBN
To understand contention on Australia's NBN, you need to understand one key piece of infrastructure: the CVC, or Connectivity Virtual Circuit.
The CVC is wholesale bandwidth that RSPs purchase from NBN Co to carry their customers' traffic from the local node (called a Point of Interconnect, or POI) through to the internet. Think of it as a pipe between the local NBN exchange and the broader internet. RSPs buy a certain amount of capacity in that pipe, and every customer in that RSP's footprint at that POI shares it.
Historically, this was where the NBN's congestion problems lived. Because CVC was charged per megabit per second on top of access fees, RSPs faced a direct financial incentive to buy less of it. The economics pushed providers to under-provision, and the result — particularly between 2017 and 2020 — was the "NBN slow lanes" that became a national frustration. Speed tests from 6 PM onwards showed figures that bore no resemblance to plan speeds, because RSPs had simply not purchased enough CVC to serve their customer bases at peak times.
NBN Co moved to address this by bundling CVC into higher speed tiers from 2023, effectively eliminating the per-Mbps CVC charge for customers on certain plans and removing the financial disincentive for RSPs to provision adequately. The result has been a meaningful improvement in NBN speeds at peak hours across the industry.
But it is important to understand that CVC was never the only source of contention on the NBN. The access network itself — the copper pair in an FTTN (Fibre to the Node) connection, the HFC cable in a hybrid-fibre-coax connection, or even the shared fibre in some FTTP arrangements — introduces its own contention at the local loop level. Multiple premises sharing a node or a coaxial segment are sharing physical capacity. Under FTTN in particular, distance from the node and the number of active users on that copper segment can significantly affect performance during peak periods.
Fixed wireless NBN adds another layer of complexity. A single tower serves a geographic area, and all connected premises in that area share the tower's capacity. As uptake increases and more premises connect, available throughput per user shrinks. This was a significant problem on early NBN fixed wireless, and it remains a consideration in areas with high tower utilisation — though NBN Co has been adding capacity and upgrading towers as part of ongoing network investment.
Understanding where contention enters the picture matters when you are evaluating your options. CVC under-provisioning by your RSP and physical access network contention are different problems with different solutions.
Business-Grade vs Consumer-Grade Contention
Not all internet plans are provisioned equally, and the difference matters significantly in practice.
Consumer NBN plans are priced for a mass market. Margins are thin, churn is high, and RSPs optimise their CVC provisioning for average-case performance rather than peak-case performance. If most customers are happy most of the time, the product is considered fit for purpose — even if a subset of customers experience degraded performance during peak hours.
Business NBN plans operate on a different set of economics. The customer base is smaller and more stable. Higher monthly pricing funds more generous wholesale capacity provisioning. Quality RSPs who specialise in business connectivity treat CVC allocation as a product feature rather than a cost to be minimised, because their customers notice and care far more than residential users do.
The practical difference is that a well-provisioned business-grade NBN plan from a quality RSP will maintain speeds much closer to the plan limit during business hours than a consumer plan on the same physical infrastructure. You are still on shared infrastructure, and contention still exists — but the ratio is tighter, and the headroom is greater.
This is not universal. The quality of provisioning varies significantly between RSPs. A business label on a plan is not a guarantee of better contention management — it depends entirely on how the provider has structured their wholesale capacity purchasing. This is one of the reasons that RSP selection matters as much as plan selection when it comes to business internet.
At the far end of the spectrum sits dedicated internet, also called enterprise ethernet or dedicated fibre. Dedicated circuits provide a reserved, symmetrical connection from your premises to the internet with no sharing at any point in the path. Contention ratio is effectively 1:1. The bandwidth you are sold is the bandwidth you get, at all hours, under all conditions. The trade-off is cost — dedicated internet is significantly more expensive than NBN services — but for businesses where internet connectivity is mission-critical, it is often the right answer.
How to Tell If Contention Is Affecting Your Business
Before spending money on an upgrade, it is worth confirming that contention is actually the issue. The test is straightforward.
Run a speed test using a tool like speedtest.net or fast.com at three different times.
The first test should be very early in the morning — 6:30 AM or 7:00 AM, before the business day begins and the surrounding area is fully active. This gives you a baseline approximating what your connection can deliver when shared infrastructure is lightly loaded.
The second test should be during peak business hours — 10:00 AM is a good target. The third should be mid-afternoon, around 3:00 PM, when conference calls and collaborative work tend to peak.
Do this across multiple days — at least three to five — to build a pattern rather than relying on a single data point. If your early-morning results are significantly higher than your peak-hour results (30% or more is a meaningful gap), contention is almost certainly a contributing factor. If results are broadly consistent across all times of day, the issue is likely elsewhere: equipment, Wi-Fi congestion, or a genuine plan limitation.
Document the results with timestamps. If you decide to escalate to your RSP or switch providers, that evidence is far more compelling than a verbal complaint. It is also worth testing at the modem level rather than over Wi-Fi — connect a laptop directly via ethernet to isolate the WAN connection specifically.
For a more detailed look at what speeds your business actually needs, the business internet speed requirements guide walks through calculating your bandwidth needs by application type and team size.
Solutions to Contention Problems
Once you have confirmed that contention is affecting your business, there are several paths forward. The right one depends on your location, your current plan, and the severity of the impact.
Upgrade to a business-grade plan from a quality RSP
If you are currently on a consumer NBN plan or a business plan with an RSP that does not adequately provision for business usage, switching to a specialist business internet provider is often the most effective and cost-efficient fix. The difference in provisioning approach between a consumer-focused RSP and a business-focused one can be substantial, even on identical physical infrastructure.
When evaluating providers, ask directly about their CVC allocation approach and typical contention ratios for business customers. A provider that cannot or will not answer this question clearly is probably not optimising for business performance.
Upgrade your speed tier
Moving from a 50 Mbps plan to a 100 Mbps plan, or from 100 Mbps to 250 Mbps, does more than just increase your maximum potential speed. It also provides more headroom against contention. If contention is reducing your effective throughput to 60% of plan speed, 60% of 250 Mbps is still more than 60% of 100 Mbps.
This is not a complete solution — you are still on shared infrastructure — but it is a pragmatic way to reduce the real-world impact of contention without changing technology or provider.
Consider fixed wireless or alternative technologies
In some locations, fixed wireless internet operates on less-congested infrastructure than NBN. This depends heavily on local tower utilisation. In areas where fixed wireless towers are not oversubscribed, performance during business hours can be substantially more consistent than equivalent NBN services.
Fixed wireless internet for business is worth evaluating if NBN options at your address are limited to older technologies like FTTN, where physical line quality compounds the contention problem.
Upgrade to dedicated internet
For businesses where consistent, guaranteed performance is non-negotiable, dedicated internet eliminates contention entirely. Enterprise ethernet circuits provide a fixed, committed information rate — the speed you purchase is the speed you get, 24 hours a day, including during business hours.
Dedicated internet is appropriate for businesses running large-scale VoIP deployments, high-volume cloud operations, real-time data processing, or multi-site SD-WAN architectures. The cost premium over NBN is significant, but so is the performance and reliability difference.
Contention and VoIP — A Specific Risk
Most of the contention discussion to this point has focused on throughput — the speed of downloads and uploads. But for businesses using VoIP (Voice over Internet Protocol) for their phone systems, the more critical measure is not throughput but latency and jitter.
Latency is the time it takes for a packet to travel from your premises to the other end of a call. Jitter is the variation in that travel time from packet to packet. VoIP calls encode voice as a stream of small packets sent and received in real time. If those packets are delayed (high latency) or arrive unevenly (high jitter), the audio breaks up, voices sound robotic or choppy, and calls become difficult to hold.
A single HD voice call uses around 85–100 kbps — far within even modest internet plans. The problem is not throughput. It is what contention does to packet timing. When a network path is congested, packets queue at bottlenecks and the resulting variable delay plays havoc with voice quality even when average throughput appears adequate. You can run a 100 Mbps speed test during a VoIP call and see acceptable results while the call itself sounds terrible, because speed tests tolerate jitter, and voice calls do not.
For more detail on how much bandwidth VoIP actually requires and how to configure your network correctly, the VoIP bandwidth requirements guide covers the specifics by call volume and codec type.
This is why businesses with VoIP phone systems have a higher stake in choosing a low-contention internet solution than businesses that use internet primarily for web browsing and file access. If your phone system runs over your internet connection, the quality of that connection during business hours is directly audible to your clients on every call.
The solution for VoIP-heavy businesses is either a business-grade internet service with demonstrated low-contention performance during business hours, or dedicated internet that removes contention from the equation entirely. Quality of Service (QoS) configuration on your router can help prioritise voice traffic over data traffic on your local network, but QoS cannot fix congestion that occurs upstream of your premises in the RSP's network.
How Pickle Manages Contention for Business Customers
Pickle's business internet products are designed around the realities of how Australian businesses actually use connectivity during the working day.
Business hours are when your connectivity needs to perform, not when it can afford to degrade. Pickle provisions wholesale capacity with business usage patterns in mind — not the statistical averages that work for residential customers but fail the moment an office full of people starts their day simultaneously.
For businesses on the NBN, Pickle's plans are structured to minimise the congestion gap between off-peak and peak performance. For businesses where NBN cannot meet requirements, Pickle offers dedicated internet and enterprise ethernet options that remove contention from the equation entirely.
If you have been living with slow internet during business hours and are not sure whether the problem is contention, your RSP's provisioning, your technology type, or something else entirely, Pickle can help work through it. There is no single answer that fits every situation — the right path depends on your technology availability, usage profile, and tolerance for variability.
The comparison between NBN business and residential plans is a useful starting point if you are weighing up whether to move from a residential-grade service to a business one.
To speak with the Pickle team about your business internet options, call 1300 688 588 or email [email protected].
Frequently Asked Questions
Q: What is a good contention ratio for business internet?
A: For business internet, a contention ratio of 10:1 or lower is generally considered good — meaning no more than ten customers share the capacity provisioned for one. Consumer-grade NBN services can operate at 50:1 or higher during peak periods. Dedicated internet services operate at 1:1, meaning no sharing at all. The lower the ratio, the more consistent your performance will be during business hours. When evaluating business internet providers, asking about their typical contention ratios for business customers is a reasonable and legitimate question.
Q: Does NBN have a contention ratio?
A: Yes. The NBN is a shared network, and contention exists at multiple levels: in the RSP's CVC allocation (the wholesale bandwidth the RSP purchases from NBN Co), and in the physical access network connecting premises to the nearest node or exchange. NBN Co's restructured CVC pricing from 2023 has reduced the incentive for RSPs to under-provision CVC, which has improved average peak-hour performance across the industry. However, contention has not been eliminated — it has been reduced. The degree of contention you experience on NBN depends significantly on your RSP's provisioning practices and the technology type at your address.
Q: Why is my internet slower during the day than in the evenings?
A: This is almost always a contention effect. During the day, businesses across your area are all active simultaneously — on video calls, accessing cloud platforms, uploading and downloading files. This concurrent demand compresses the available bandwidth on shared infrastructure, and everyone's effective speed drops. In the evenings, residential traffic is a mix of activities spread across different times (streaming, browsing, gaming) with lower concurrent peaks, and business traffic is largely absent. The shared infrastructure is less loaded, and individual speeds rise accordingly. If your internet consistently performs significantly better before 8 AM or after 6 PM than it does between 9 AM and 5 PM, contention is the most likely explanation.
Q: Does a higher speed plan reduce contention problems?
A: Partially, yes. Upgrading your speed tier gives you more headroom. If contention reduces effective throughput to 60% of plan speed, 60% of 250 Mbps delivers 150 Mbps, whereas 60% of 100 Mbps delivers only 60 Mbps. So a higher speed tier does improve real-world performance even under contention. However, this approach has limits. It addresses the symptom rather than the cause, and very heavily congested infrastructure can compress performance at any speed tier. Upgrading your speed tier is a useful step when combined with moving to a quality business-grade RSP — it is less effective on its own if the underlying provisioning problem remains.
Q: Is there any internet connection with no contention?
A: Yes. Dedicated internet services — also called enterprise ethernet, dedicated fibre, or committed information rate (CIR) services — provide a reserved connection with no shared capacity at any point in the path. The bandwidth you purchase is yours exclusively, at all times. These services are not sold on "up to" speeds; they are sold on guaranteed speeds with contracted uptime and performance SLAs. Dedicated internet is substantially more expensive than NBN services, but for businesses where consistent, predictable internet performance is critical — particularly those running large VoIP deployments, real-time cloud systems, or multi-site networks — the performance guarantee justifies the cost premium.